The process products are used, inter alia, as intermediates in the production of fuel additives (U.S. Pat. No. 3,275,554; DE-A-21 25 039 and DE-A-36 11 230), surfactants, drugs and crop protection agents, hardeners for epoxy resins, catalysts for polyurethanes, intermediates for the preparation of quaternary ammonium compounds, plasticizers, corrosion inhibitors, synthetic resins, ion exchangers, textile assistants, dyes, vulcanization accelerators and/or emulsifiers.
U.S. Pat. No. 4,153,581 (Habermann) relates to amination of alcohols, aldehydes or ketones by means of specific Co/Cu catalysts comprising Fe, Zn and/or Zr.
U.S. Pat. No. 4,152,353 (Dow) relates to amination of alcohols, aldehydes or ketones by means of specific Ni/Cu catalysts comprising Fe, Zn and/or Zr.
EP-A1-382 049 (BASF AG) discloses catalysts which comprise oxygen-comprising zirconium, copper, cobalt and nickel compounds and processes for the hydrogenative amination of alcohols. The preferred zirconium oxide content of these catalysts is from 70 to 80% by weight (loc. cit.: page 2, last paragraph; page 3, 3rd paragraph; examples). Although these catalysts have a good activity and selectivity, they display operating lives which are in need of improvement.
EP-A2-514 692 (BASF AG) discloses catalysts comprising copper oxide, nickel oxide and/or cobalt oxide, zirconium oxide and/or aluminum oxide for the catalytic amination of alcohols by means of ammonia or primary amines and hydrogen in the gas phase. This patent application teaches that in these catalysts the atomic ratio of nickel to copper has to be from 0.1 to 1.0, preferably from 0.2 to 0.5 (a loc. cit.: example 1), since otherwise there is increased formation of yield-reducing by-products in the amination of alcohols (loc. cit.: examples 6 and 12). Aluminum oxide is preferably used as support (loc. cit.: examples 1 to 5 and 7 to 11).
EP-A1-696 572 and EP-A-697 395 (both BASF AG) disclose catalysts comprising nickel oxide, copper oxide, zirconium oxide and molybdenum oxide for the catalytic amination of alcohols by means of nitrogen compounds and hydrogen. Although high conversions are achieved using these catalysts, by-products which themselves, or after conversion into subsequent products, can interfere in the work-up can be formed.
EP-A2-905 122 (BASF AG) describes a process for preparing amines from alcohols and nitrogen compounds using a catalyst whose catalytically active composition comprises oxygen-comprising compounds of zirconium, copper and nickel and no oxygen-comprising compounds of cobalt or molybdenum.
EP-A-1 035 106 (BASF AG) relates to the use of catalysts comprising oxygen-comprising compounds of zirconium, copper and nickel for preparing amines by aminative hydrogenation of aldehydes or ketones.
EP-A1-963 975 and EP-A2-1 106 600 (both BASF AG) describe processes for preparing amines from alcohols or aldehydes or ketones and nitrogen compounds using a catalyst whose catalytically active composition comprises 22-40% by weight (or 22-45% by weight) of oxygen-comprising compounds of zirconium, 1-30% by weight of oxygen-comprising compounds of copper and 15-50% by weight (or 5-50% by weight) of oxygen-comprising compounds of each of nickel and cobalt.
WO-A-03/076386 and EP-A1-1 431 271 (both BASF AG) also teach catalysts of the abovementioned type for aminations.
WO-A1-03/051508 (Huntsman Petrochemical Corp.) relates to processes for the amination of alcohols using specific Cu/Ni/Zr/Sn-comprising catalysts which, in a further embodiment, comprise Cr instead of Zr (see page 4, lines 10-16).
The European patent application No. 06101339.7 of Feb. 6, 2006 (BASF AG) describes a process for preparing aminodiglycol (ADG) and morpholine by reaction of diethylene glycol (DEG) with ammonia in the presence of a heterogeneous transition metal catalyst, in which the catalytically active composition of the catalyst prior to treatment with hydrogen comprises oxygen-comprising compounds of aluminum and/or zirconium, copper, nickel and cobalt and the shaped catalyst body has specific dimensions.
Four parallel European patent applications having the same filing date (all BASF AG) relate to particular doped catalysts comprising zirconium dioxide, copper and nickel and their use in processes for preparing an amine by reaction of a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine.
When the very active catalysts of the prior art, in particular the catalysts according to EP-A1-696 572, EP-A1-963 975 and EP-A2-1 106 600 (see above) are used, increased decarbonylation of the carbonyl function (possibly formed as an intermediate) of the starting materials (alcohols, aldehyde, ketone) occurs at elevated temperature. The formation of methane by hydrogenation of carbon monoxide (CO) leads, owing to the large quantity of heat of hydrogenation liberated, to a risk of a “runaway reaction”, i.e. an uncontrolled temperature increase in the reactor. If CO is scavenged by amines, formation of secondary components comprising methyl groups results.
In the amination of diethylene glycol (DEG), there is, for example, increased formation of undesirable methoxyethanol or methoxyethylamine.
In the example of the amination of diethylene glycol (DEG), the “decarbonylation” is considered to be, in particular, the sum of undesirable components (methanol, methoxyethanol, methoxyethylamine, N-methylmorpholine and methoxyethyl-morpholine), which are formed from DEG by a reaction network via methoxyethanol:

As reaction mechanism of the amination of primary or secondary alcohols, it is assumed that the alcohol is initially dehydrogenated at a metal center to form the corresponding aldehyde. The copper is presumably of particular importance as dehydrogenation component. If aldehydes are used for the amination, this step is eliminated.
The aldehyde formed or used can be aminated by reaction with ammonia or primary or secondary amine with elimination of water and subsequent hydrogenation. This condensation of the aldehyde with the abovementioned nitrogen compound is presumably catalyzed by acid sites in the catalyst. However, the aldehyde can also be decarbonylated in an undesirable secondary reaction, i.e. the aldehyde function is split off as CO. The decarbonylation or methanization presumably takes place at a metallic center. The CO is hydrogenated to methane over the hydrogenation catalyst, so that the formation of methane acts as an indicator of the extent of decarbonylation. The decarbonylation forms the abovementioned undesirable by-products such as, in the abovementioned case, methoxyethanol and/or methoxyethylamine.
The undesirable condensation of the aldehyde with ammonia or primary or secondary amine and the undesirable decarbonylation of the aldehyde are parallel reactions of which the undesirable condensation is presumably acid-catalyzed while the undesirable decarbonylation is catalyzed by metallic centers.